1. Field of the Invention
The present invention relates to apparatuses for controlling servomotors of electric injection molding machines. The invention particularly relates to an apparatus that provides synchronous control for several servomotors of an electric injection molding machine.
2. Description of Related Art
In general, an electric injection molding machine includes one servomotor for driving the electric injection molding machine to inject melted resin. As the size of the electric injection molding machine becomes larger, greater efficiency of the servomotor is required as well. Thus, other electric injection molding machines use multiple synchronous servomotors. Referring to FIG. 1, a control apparatus 10 of an electric injection molding machine is provided for controlling at least two servomotors 31, 32, according to the prior art. The servomotors 31, 32 drive two mastering members 310, 320 respectively. The mastering member 310 includes a ball screw 314 and a screw cap 312. The mastering member 320 includes a ball screw 324 and a screw cap 322. The screw caps 312, 322 are connected by a rigid member 33. An injection screw 34 is mounted to the rigid member 33. The control apparatus 10 simultaneously outputs two signals to the servomotors 31, 32, for synchronously driving the ball screws 314, 324 and the rigid member 33 to move. The injection screw 34 is driven to a tube 35 coupled with the injection screw 34 to inject melted resin into a cavity 36. However, it is difficult for the servomotors 31, 32 to act synchronously.
What is needed, therefore, is to provide a better apparatus for applying synchronous servomotors of an electric injection molding machine to improve an accuracy of the electric injection molding machine.